In this research, we investigated the cryopreservation techniques generally applicable to tropical germplasms of photosynthetic organisms such as higher plants and microalgae useful for searching novel bioactive metabolites in Pharmaceutical Science field. We also attempted to diffuse these techniques in South-east Asian countries in which ecosystem in rainforest is rapidly destructed by environmental pollution many precious species of higher plants and microalgae are on the way to extinction.As a fundamental research using plant root and green alga, we found a phytohormone, abscisic acid(ABA), could induce tolerance to dehydration and then freezing. ABA-pretreatment increased the survival rates in these materials after freezing in liquid nitrogen. We applied this pretreatment to several plants and algae and succeeded their cryopreservation.We attempted to search novel bioactive metabolites in microalgae in those areas under cooperation with foreign researchers. Several metabolites showing strong growth inhibitory activities and a biosurfactant could be isolated from freshwater cyanobacteria isolated in Thailand and Indonesia.Finally, we made efforts to diffuse the developed cryopreservation techniques in Thailand and Indonesia as generally applicable ones for conservation of useful tropical plant and algal germplasms. We visited these countries several times and gave lectures and technical workshops to encourage the consciousness for importance of tropical germplasms and increase the individual techniques of cryopreservation.